Ok something is wrong with my period?

i have had my period 2 whole years and i am almost a freshman but for the past 6 months i havent had one and i am relly startin to worry! and no i am not ually active! i am like one of the most christian people ever! but i am really beginin to get scared!! i mean could it be cancer or is something else really wrong? please help me! and its about to be the 7th month!